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biology > Exchange > Flashcards

Exchange Flashcards

1
Q

What substances must be exchanged with the environment in an organism?

A

Heat
Respiratory gases
Excretory products
Nutrients

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2
Q

What factors affect the rate of exchange?

A 
Length of diffusion pathway
Surface area
Concentration and pressure gradient 
Carrier proteins
Temperature
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3
Q

What are the methods of exchange?

A

Active, bulk and Co transport
Osmosis
Simple facilitated diffusion

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4
Q

How do you calculate the volume and surface area of a sphere?

A

SA=4x3.124xr^2

Volume= 4/3x3.142xr^3

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5
Q

Why is sa:vol smaller in large animals?

A

As size increases volume increases faster than sa

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6
Q

Why do mammals require a specialised exchange surface and transport system?

A

Small sa:vol
Not enough can diffuse in and out to supply volume
Large diffusion gradient= can’t reach cell quick enough

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7
Q

What are the adaptions of a specialised exchange surface? Give examples

A

Layer of cells one cell thick

Movement of internal and external mediums

Large sa:vol

Selectively permeable membrane

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8
Q

What is the advantage of having a large surface area?

A

More carrier and channel proteins

More places to diffuse across

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9
Q

What is the disadvantage of having a thin surface membrane?

How is this overcome?

A

Easily damaged and dehydrated

Inside organism

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10
Q

Why do mice have a high metabolic rate?

A

Move lots more

Large sa:vol

Heat lost easily
Constantly replaced by energy released via Respiration
High rate of Respiration

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11
Q

Why do single celled organisms not need a circulatory system?

A

Short diffusion pathway meaning substance can be supplied quick enough

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12
Q

Why do single celled organisms have a high rate of exchange?

A

Large sa:vol

Short diffusion pathway

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13
Q

How are the tracheas in humans and insects similar?

A

Humans = cartilage

Insects= chitin

Rings

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14
Q

What is a spiracle and how is it adapted?

A

Pore in side of insects

Hairs and ability to close to conserve water

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15
Q

Why are insects limited to the size they can grow to?

A

Must remain small to retain short diffusion pathway

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16
Q

How are Respiratory gases moved in an insect?

A

Mass tansport: Abdominal pumping

Drawn in (lactate produced lowering wp so water drawn into muscle cells so last part= gas phase)

Diffusion down partial pressure gradient

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17
Q

Describe the structure of the gills

A

Gill arches

Gill filaments

Gill lamella

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18
Q

What is the operculum ?

A

Hard bony flap that deoxygenated water leaves out of

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19
Q

How are the gills adapted?

A

Thin surface (one cell thick)

Movement of external and external mediums

Good blood supply

Large sa

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20
Q

Why might fish die in warm water?

A

Oxygen is less soluble in warm water (already not very soluble)

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21
Q

Why do fish require specialised gas exchange surfaces?

A

Small sa:vol

Waterpriof and gas tight outer coating

Oxygen not very soluble in water

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22
Q

What best describes this mechanism: blood flows one way as water flow in the opposite direction?

A

Countercurrent exchange principle

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23
Q

Why is the countercurrent exchange principle important?

A

Prevents equilibrium being reached

Diffusion across whole length of gill

Blood always next to wtae reith higher oxygen concentration

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24
Q

What is the opposite to countercurrent flow?

A

Parallel flow

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25
During the day what is the net movement of co2 and o2 in a leaf? Why?
Co2 in o2 out Rate of Photosynthesis exceeds respiration
26
During the night what is the net movement of co2 and o2 in a leaf? Why
O2 in co2 out Photosynthesis doesn't occur at night
27
What occurs at dawn and dusk?
Compensation point as rate of Photosynthesis and Respiration are equal No net diffusion
28
How do guard cells open and close the stomata?
Make sugar Lower wp Water moves in Makes turgid as thick inflexible inner wall creates opening
29
What is different about guard cells?
Have thick and inflexible inner wall Have chloroplasts to make sugar to lower wp
30
What state are guard cells in when the stomata is closed?
Plasmolysis
31
Why do plants not have ventilation or ma's transport system?
Have thin diffusion pathway so can diffuse Ventilation would cause too much water loss
32
Adaptions of leaf for gas exchange
Flat and thin (large sa and short diffusion pathway) Air spaces in mesophyll= large sa and diffusion in gas phase so quicker
33
How do insects limit water loss?
Hairs around spiracles trap moist air Waterproof cuticle over chitin exoskeleton Spiracles can close Small sa:vol = minimise área over which water lost
34
How do plants limit water loss?
Close stomata Waxy cuticle
35
How do xerphytic plants reduce water loss?
Reduce sa = circular cross section Curl leaves, hairs around stomata, sunken stomata= trap moist air Thick Waxy cuticle
36
Why might having needle shaped leaves be contravertial for plants?
Smaller sa:vol Less gas exchange
37
What is a xerphytic plant?
Plant adapted to live in areas of short water supply
38
Give examples of xerphytic conditions
Salt marshes= hard to obtain water High wind speeds= high conc gradient Sand dunes= water drains away Very cold= water trapped in ice
39
Why are large volumes of gases exchanged in large organisms?
High body temp= high metabolic rate= more respirtion Many cells to supply
40
What structure does air pass to get to the lungs?
``` Nasal cavity Epiglottis Larynx Trachea Bronchus Bronchioles Alveoli ```
41
Why are the lungs inside the body?
The prevent dehydration and damage due to thin layer of one cell
42
What are the lungs?
Two lobed structures
43
Describe the structure or the trachea
C shaped ring of cartilage =prevent collapse Thick Smooth muscle elastic fibers Ciliated epithelial cells=waft mucus up Goblet cells= produce mucus
44
Describe the structure of the Bronchus
Small sections of cartilage Ciliated epithelial cells Goblet cells Smooth muscles Glands
45
Describe the changing structure of the Bronchioles as you go towards the alveoli
More smooth muscle less/no cartilage Contact to regulate ventilation Made of epithelial cells
46
Describe the structure of a alveoli bundle
Alveoli with tissue fluid, collagen and elastic fibres between them Network of capillaries
47
Describe the structure of a alveoli and their function
Squamous epithelial cells= reduced diffusion pathway Water= because cell membranes are permeable Elastic fibres allow recoiling
48
Describe how the capillaries near the alveoli are adapted for gas exchange
Squamous endothelial cells=short diffusion pathway Red blood cells compressed up to walls Blood is slowed
49
Why might alveoli seem to be different sizes when looked at through a microscope?
Cut in different planes
50
How are the lungs adapted for gas exchange?
Short diffusion pathway: Squamous endo and epithelial cells Compressed erythrocytes Maintain conc gradient: Elastic fibres= recoil Flow of blood Ventilation Large sa: Alveoli and pulmonary capillary walls Flow of blood slows= more time to diffuse Alveoli packed closely together
51
Why do people with asthma struggle to breath?
Muscles in Bronchus and Bronchioles contract reducing diameter of lumen Goblet cells produce excess thick mucus Reduced air flow
52
What is emphysema?
When the walls of alveoli break down and fuse Large alveoli of reduced number = smaller sa:vol Thick walls = long diffusion pathway Elastin not replaced
53
What is fibrosis and why does it cause breathing difficulties?
Elastic fibres in lungs become stiff Reduce volume of lungs (can't strech)
54
What are the risk factor for lung disease?
Genetic makeup Smoking Infection Occupation Air pollution
55
Describe inhalation
External intercostal muscles contract, internal relax Diaphragm contracts and flattens from dome shape Sternum and runs move up and out Elastic fibres strech Volume in lungs increases pressure in lungs decreases below atmospheric pressure Air moves in down pressure gradient
56
When does the cartilage in the trachea provide its function?
During inspiration and pressure drops
57
Define inhalation
Pressure in lungs decreases below atmospheric pressure and air moves into lungs
58
Define exhalation
Pressure in lungs increases above atmospheric pressure air is forced out of lungs
59
Describe exhalation
Internal intercostal muscles contract (only during exercise ) and external relax Elastic fibres of lungs recoil Diaphragm relaxes and returns to dome shape Sternum and ribs move in and down Volume of lungs decreases and pressure increases above atmospheric pressure Air is expelled
60
Is inspiration active?
Yes because external intercostal muscles contract
61
Is expiration active?
No passive when at rest as elastic fibres recoil
62
What is the equation for pulmonary ventilation?
Pulmonary ventillation= | Tidal volume X breathing rate
63
Define and give units for pulmonary ventilation
Volume of air moved into lungs in a minute Dm^3min^-1
64
Define and give units for tidal volume
Maximum volume of air inspired after maximum exhalation at rest Dm^3
65
Define and give units for breathing rate
Breaths per min Breathsmin^-1
66
How does reducing stomata diameter help plants survive?
Less water lost More water available for Photosynthesis

biology (28 decks)

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